1. Which process results in the production of haploid gametes in animals?
(A) Mitosis
(B) Meiosis
(C) Binary fission
(D) Budding
Answer: (B)
Explanation: Meiosis reduces the chromosome number by half, producing haploid gametes (sperm and eggs) essential for sexual reproduction. Mitosis produces identical diploid cells.
2. Which part of the human digestive system absorbs most nutrients?
(A) Stomach
(B) Small intestine
(C) Large intestine
(D) Esophagus
Answer: (B)
Explanation: The small intestine, with its villi and microvilli, is specialized for efficient absorption of nutrients from digested food.
3. Which gas, produced during photosynthesis, is vital for aerobic respiration?
(A) Carbon dioxide
(B) Oxygen
(C) Nitrogen
(D) Methane
Answer: (B)
Explanation: Oxygen is released as a byproduct of photosynthesis and is essential for aerobic respiration in most organisms.
4. Which middle ear structure amplifies sound vibrations?
(A) Cochlea
(B) Ossicles
(C) Eardrum
(D) Auditory nerve
Answer: (B)
Explanation: The ossicles (malleus, incus, stapes) transmit and amplify sound from the eardrum to the inner ear.
5. The scientific study of fungi is called:
(A) Mycology
(B) Bryology
(C) Phycology
(D) Ethology
Answer: (A)
Explanation: Mycology is the branch of biology dealing with fungi, including their genetics and ecology.
6. Which hormone triggers ovulation in females?
(A) Estrogen
(B) Progesterone
(C) Luteinizing hormone
(D) Oxytocin
Answer: (C)
Explanation: Luteinizing hormone (LH) surges mid-cycle, causing the release of an egg from the ovary.
7. Which ecological interaction benefits both participating species?
(A) Parasitism
(B) Mutualism
(C) Commensalism
(D) Predation
Answer: (B)
Explanation: Mutualism is a symbiotic relationship where both species derive a benefit, e.g., bees and flowering plants.
8. What is the main substrate for cellular respiration?
(A) Glucose
(B) Protein
(C) Lipid
(D) Nucleic acid
Answer: (A)
Explanation: Glucose is the primary molecule broken down during cellular respiration to release energy (ATP).
9. After fertilization, which floral part develops into a fruit?
(A) Stamen
(B) Petal
(C) Ovary
(D) Sepal
Answer: (C)
Explanation: The ovary matures into a fruit, enclosing the seeds after fertilization.
10. The loss of water vapor from plant leaves is called:
(A) Guttation
(B) Transpiration
(C) Exudation
(D) Evaporation
Answer: (B)
Explanation: Transpiration is the process of water vapor loss through stomata, crucial for nutrient transport and cooling.
11. Which vessel returns oxygenated blood from the lungs to the heart?
(A) Pulmonary artery
(B) Pulmonary vein
(C) Aorta
(D) Vena cava
Answer: (B)
Explanation: The pulmonary vein is unique in carrying oxygenated blood from the lungs to the left atrium of the heart.
12. The study of animal behavior is known as:
(A) Ethology
(B) Ecology
(C) Zoology
(D) Ornithology
Answer: (A)
Explanation: Ethology focuses on the behavioral patterns of animals, both innate and learned.
13. Which enzyme breaks down starch into simpler sugars?
(A) Lipase
(B) Amylase
(C) Protease
(D) Nuclease
Answer: (B)
Explanation: Amylase, present in saliva and pancreatic juice, hydrolyzes starch to maltose and glucose.
14. Reproduction involving fusion of gametes is called:
(A) Asexual reproduction
(B) Sexual reproduction
(C) Vegetative propagation
(D) Budding
Answer: (B)
Explanation: Sexual reproduction involves the fusion of male and female gametes, resulting in genetic variation.
15. What is the main role of hemoglobin in blood?
(A) Clotting
(B) Immunity
(C) Oxygen transport
(D) Nutrient transport
Answer: (C)
Explanation: Hemoglobin binds oxygen in red blood cells, transporting it from the lungs to tissues.
16. Which ecosystem type has the highest biodiversity?
(A) Desert
(B) Tundra
(C) Tropical rainforest
(D) Grassland
Answer: (C)
Explanation: Tropical rainforests are the richest in species diversity due to stable climate and abundant resources.
17. Division of somatic cells occurs through:
(A) Meiosis
(B) Mitosis
(C) Cytokinesis
(D) Binary fission
Answer: (B)
Explanation: Mitosis produces two genetically identical diploid cells for growth and repair.
18. Which organ stores bile in humans?
(A) Pancreas
(B) Liver
(C) Gallbladder
(D) Stomach
Answer: (C)
Explanation: The gallbladder stores and concentrates bile produced by the liver for fat digestion.
19. Transfer of pollen from anther to stigma is called:
(A) Fertilization
(B) Pollination
(C) Germination
(D) Dispersal
Answer: (B)
Explanation: Pollination enables fertilization by bringing male and female gametes together in plants.
20. Night blindness is caused by deficiency of:
(A) Vitamin A
(B) Vitamin B1
(C) Vitamin C
(D) Vitamin D
Answer: (A)
Explanation: Vitamin A is essential for the formation of visual pigments; its deficiency impairs night vision.
21. Which part of the brain controls balance and coordination?
(A) Cerebrum
(B) Cerebellum
(C) Medulla oblongata
(D) Hypothalamus
Answer: (B)
Explanation: The cerebellum integrates sensory input to maintain posture, balance, and coordinate movements.
22. The main source of nitrogen for plants is:
(A) Air
(B) Soil
(C) Water
(D) Sunlight
Answer: (B)
Explanation: Plants absorb nitrogen as nitrates or ammonium from soil, not directly from atmospheric nitrogen.
23. Which RNA type carries amino acids for protein synthesis?
(A) mRNA
(B) tRNA
(C) rRNA
(D) snRNA
Answer: (B)
Explanation: tRNA (transfer RNA) brings specific amino acids to the ribosome during translation.
24. Gradual change in species over generations is termed:
(A) Adaptation
(B) Evolution
(C) Mutation
(D) Speciation
Answer: (B)
Explanation: Evolution describes the genetic changes in populations over time, leading to new species.
25. Which hormone accelerates fruit ripening?
(A) Auxin
(B) Gibberellin
(C) Ethylene
(D) Cytokinin
Answer: (C)
Explanation: Ethylene is a gaseous plant hormone that triggers fruit ripening and leaf abscission.
26. The blood-filtering structure in the kidney is:
(A) Nephron
(B) Ureter
(C) Urethra
(D) Bladder
Answer: (A)
Explanation: Each nephron filters blood, reabsorbs useful substances, and forms urine.
27. A symbiotic relationship where one benefits and the other is unaffected is:
(A) Mutualism
(B) Commensalism
(C) Parasitism
(D) Competition
Answer: (B)
Explanation: In commensalism, one species benefits, the other is neither helped nor harmed.
28. Malaria is caused by:
(A) Bacteria
(B) Virus
(C) Protozoan
(D) Fungus
Answer: (C)
Explanation: Malaria is caused by the Plasmodium protozoan, transmitted by Anopheles mosquitoes.
29. The main function of stomata in plants is:
(A) Nutrient absorption
(B) Gas exchange
(C) Water transport
(D) Photosynthesis
Answer: (B)
Explanation: Stomata are pores that regulate gas exchange (CO₂ in, O₂ out) and water vapor loss.
30. Down syndrome is caused by:
(A) Sickle cell anemia
(B) Extra chromosome 21
(C) Cystic fibrosis
(D) Hemophilia
Answer: (B)
Explanation: Down syndrome results from trisomy 21, an extra copy of chromosome 21.
31. Adult red blood cells are produced in:
(A) Liver
(B) Spleen
(C) Bone marrow
(D) Kidney
Answer: (C)
Explanation: Bone marrow is the site of hematopoiesis, producing red and white blood cells.
32. The breakdown of complex molecules into simpler ones is called:
(A) Anabolism
(B) Catabolism
(C) Metabolism
(D) Homeostasis
Answer: (B)
Explanation: Catabolism releases energy by breaking down complex molecules, e.g., during cellular respiration.
33. Tissue connecting muscles to bones is:
(A) Ligament
(B) Tendon
(C) Cartilage
(D) Adipose tissue
Answer: (B)
Explanation: Tendons are strong connective tissues that attach muscles to bones.
34. The primary energy source for Earth’s climate is:
(A) Geothermal heat
(B) Sun
(C) Fossil fuels
(D) Ocean currents
Answer: (B)
Explanation: Solar energy drives weather, climate, and life processes on Earth.
35. Viruses store genetic information as:
(A) DNA only
(B) RNA only
(C) DNA or RNA
(D) Proteins
Answer: (C)
Explanation: Viruses may use either DNA or RNA as their genetic material, never proteins.
36. The process converting atmospheric nitrogen to usable forms for plants is:
(A) Nitrification
(B) Denitrification
(C) Nitrogen fixation
(D) Ammonification
Answer: (C)
Explanation: Nitrogen fixation by bacteria converts N₂ gas to ammonia, usable by plants.
37. Which part of the eye regulates light entry?
(A) Cornea
(B) Iris
(C) Lens
(D) Retina
Answer: (B)
Explanation: The iris adjusts pupil size, controlling the amount of light entering the eye.
38. A group of similar ecosystems is called:
(A) Habitat
(B) Biome
(C) Niche
(D) Community
Answer: (B)
Explanation: A biome encompasses multiple ecosystems with similar climate and organisms.
39. Which hormone controls water reabsorption in kidneys?
(A) Insulin
(B) Antidiuretic hormone
(C) Cortisol
(D) Thyroxine
Answer: (B)
Explanation: ADH increases water reabsorption in kidney tubules, helping maintain fluid balance.
40. The joint type allowing the greatest range of motion is:
(A) Hinge joint
(B) Pivot joint
(C) Ball-and-socket joint
(D) Suture joint
Answer: (C)
Explanation: Ball-and-socket joints (shoulder, hip) allow movement in multiple directions.